You can't use the expression pedals to change scenes. They're there to control whatever parameters you want to control in the effects. Almost every parameter can be assigned to an expression pedal, so how you set them up just depends on what you want to do. You can also control the parameters associated with the looper. As to why there's two, I'd say it's just to give more flexibility.

The settings for the expression pedals are saved on a scene per scene basis (except for the looper), so if want the pedals to control certain things in certain scenes you have to save the scene with those settings (assuming you're using manual save mode; in autosave mode, they will be saved with the scene as you set them up).

1

"It is not our duty to understand the arbitrary, meaningless dictates of machines"

You're saying expression pedal 2 can be assigned to different parameters for each FX, independent from expression pedal 1?

Let's take a distortion FX as an example: so I could dial in the amount of distortion with the first expression pedal and control treble settings with the second one? Dizzy!

Well, I guess that is one limitation. You can't have different parameters in the same effect controlled by different expression pedals. But you can have different effects within the same scene controlled by different expression pedals. In the POD HD500, the expression control is similar to the M-series, but you actually could control different parameters within the same effect with different pedals.

Since you seem to be pretty familiar with the device, is there a way to save/store loops (similar to the Boss Rc's)?

No, there isn't. The looper really is meant for only on-the-fly looping. You can't load pre-recorded loops or export loops that you've made.

0

"It is not our duty to understand the arbitrary, meaningless dictates of machines"

I can't even have one expression pedal assigned to tweak parameters on individual effects and use the other expression pedal to control the volume for scenes?

Well, you could use the second expression pedal to control the volume effect in a scene, but if you use the volume effect, that eats up one of your slots in that scene. I would say that if you want to control volume, you're better off getting a dedicated volume pedal rather than a second expression pedal. They take up about the same amount of space on your board, anyway.

I don't currently have the M9. I have the M13, and I use both expression inputs. I like it because it gives me freedom to assign different parameters of different effect independently from each other. I often will assign the delay feedback (repeats) to the one so I can force a delay to go into self-oscillation very easily. I'll have the other pedal setup to control things associated with modulation. I like controlling the mix parameter of a tremolo, for example. It's nice for blending effects in slowly.

0

"It is not our duty to understand the arbitrary, meaningless dictates of machines"